Buggy code:
private assistNodeIsInterface ; boolean assistNodeIsAnnotation ; boolean assistNodeIsConstructor ; boolean assistNodeIsSuperType ; boolean assistNodeIsExtendedType ; int assistNodeInJavadoc = 0 ; boolean assistNodeCanBeSingleMemberAnnotation = false ; long targetedElement ; WorkingCopyOwner owner ; IProgressMonitor monitor ; IJavaProject javaProject ; ITypeRoot typeRoot ; CompletionParser parser ; CompletionRequestor requestor ; CompletionEngine . CompletionProblemFactory problemFactory ; ProblemReporter problemReporter ; private JavaSearchNameEnvironment noCacheNameEnvironment ; char [ ] source ; char [ ] completionToken ; char [ ] qualifiedCompletionToken ; boolean resolvingImports = false ; boolean resolvingStaticImports = false ; boolean insideQualifiedReference = false ; boolean noProposal = true ; CategorizedProblem problem = null ; char [ ] fileName = null ; int startPosition ; int actualCompletionPosition ; int endPosition ; int offset ; int tokenStart ; int tokenEnd ; int javadocTagPosition ; HashtableOfObject knownPkgs = new HashtableOfObject ( 10 ) ; HashtableOfObject knownTypes = new HashtableOfObject ( 10 ) ; Scanner nameScanner ; static final BaseTypeBinding [ ] BASE_TYPES = new BaseTypeBinding [ ] { TypeBinding . BOOLEAN , TypeBinding . BYTE , TypeBinding . CHAR , TypeBinding . DOUBLE , TypeBinding . FLOAT , TypeBinding . INT , TypeBinding . LONG , TypeBinding . SHORT , TypeBinding . VOID } ; static final int BASE_TYPES_LENGTH = CompletionEngine . BASE_TYPES . length ; static final char [ ] [ ] BASE_TYPE_NAMES = new char [ CompletionEngine . BASE_TYPES_LENGTH ] [ ] ; static final int BASE_TYPES_WITHOUT_VOID_LENGTH = ( CompletionEngine . BASE_TYPES . length ) - 1 ; static final char [ ] [ ] BASE_TYPE_NAMES_WITHOUT_VOID = new char [ CompletionEngine . BASE_TYPES_WITHOUT_VOID_LENGTH ] [ ] ; static final char [ ] classField = "class" . toCharArray ( ) ; static final char [ ] lengthField = "length" . toCharArray ( ) ; static final char [ ] cloneMethod = "clone" . toCharArray ( ) ; static final char [ ] THIS = "this" . toCharArray ( ) ; static final char [ ] THROWS = "throws" . toCharArray ( ) ; static InvocationSite FakeInvocationSite = new InvocationSite ( ) { public TypeBinding [ ] genericTypeArguments ( ) { } public boolean isSuperAccess ( ) { } public boolean isTypeAccess ( ) { } public void setActualReceiverType ( ReferenceBinding receiverType ) { } public void setDepth ( int depth ) { } public void setFieldIndex ( int depth ) { } public int sourceEnd ( ) { } public int sourceStart ( ) { } } ; private int foundTypesCount ; private ObjectVector acceptedTypes ; private int foundConstructorsCount ; private ObjectVector acceptedConstructors ; public CompletionEngine ( SearchableEnvironment nameEnvironment , CompletionRequestor requestor , Map settings , IJavaProject javaProject , WorkingCopyOwner owner , IProgressMonitor monitor ) { } public void acceptConstructor ( int modifiers , char [ ] simpleTypeName , int parameterCount , char [ ] signature , char [ ] [ ] parameterTypes , char [ ] [ ] parameterNames , int typeModifiers , char [ ] packageName , int extraFlags , String path , AccessRestriction accessRestriction ) { } private void acceptConstructors ( Scope scope ) { } public void acceptPackage ( char [ ] packageName ) { } public void acceptType ( char [ ] packageName , char [ ] simpleTypeName , char [ ] [ ] enclosingTypeNames , int modifiers , AccessRestriction accessRestriction ) { } private void acceptTypes ( Scope scope ) { } public void acceptUnresolvedName ( char [ ] name ) { } private void addExpectedType ( TypeBinding type , Scope scope ) { } private void addForbiddenBindings ( Binding binding ) { } private void addUninterestingBindings ( Binding binding ) { } private final boolean areParametersCompatibleWith ( TypeBinding [ ] parameters , TypeBinding [ ] arguments , boolean isVarargs ) { } private void buildContext ( ASTNode astNode , ASTNode astNodeParent , CompilationUnitDeclaration compilationUnitDeclaration , Binding qualifiedBinding , Scope scope ) { } private void buildTokenLocationContext ( InternalCompletionContext context , Scope scope , ASTNode astNode , ASTNode astNodeParent ) { } void checkCancel ( ) { } private boolean complete ( ASTNode astNode , ASTNode astNodeParent , ASTNode enclosingNode , CompilationUnitDeclaration compilationUnitDeclaration , Binding qualifiedBinding , Scope scope , boolean insideTypeAnnotation ) { } public void complete ( ICompilationUnit sourceUnit , int completionPosition , int pos , ITypeRoot root ) { if ( CompletionEngine . DEBUG ) { System . out . print ( "COMPLETION<seq2seq4repair_space>IN<seq2seq4repair_space>" ) ; System . out . print ( sourceUnit . getFileName ( ) ) ; System . out . print ( "<seq2seq4repair_space>AT<seq2seq4repair_space>POSITION<seq2seq4repair_space>" ) ; System . out . println ( completionPosition ) ; System . out . println ( "COMPLETION<seq2seq4repair_space>-<seq2seq4repair_space>Source<seq2seq4repair_space>:" ) ; System . out . println ( sourceUnit . getContents ( ) ) ; } if ( ( this . monitor ) != null ) this . monitor . beginTask ( Messages . engine_completing , IProgressMonitor . UNKNOWN ) ; this . requestor . beginReporting ( ) ; boolean contextAccepted = false ; try { this . fileName = sourceUnit . getFileName ( ) ; this . actualCompletionPosition = completionPosition - 1 ; this . offset = pos ; this . typeRoot = root ; this . checkCancel ( ) ; CompilationResult result = new CompilationResult ( sourceUnit , 1 , 1 , this . compilerOptions . maxProblemsPerUnit ) ; CompilationUnitDeclaration parsedUnit = this . parser . dietParse ( sourceUnit , result , this . actualCompletionPosition ) ; if ( parsedUnit != null ) { if ( CompletionEngine . DEBUG ) { System . out . println ( "COMPLETION<seq2seq4repair_space>-<seq2seq4repair_space>Diet<seq2seq4repair_space>AST<seq2seq4repair_space>:" ) ; System . out . println ( parsedUnit . toString ( ) ) ; } if ( ( parsedUnit . currentPackage ) instanceof CompletionOnPackageReference ) { contextAccepted = true ; buildContext ( parsedUnit . currentPackage , null , parsedUnit , null , null ) ; if ( ! ( this . requestor . isIgnored ( CompletionProposal . PACKAGE_REF ) ) ) { findPackages ( ( ( CompletionOnPackageReference ) ( parsedUnit . currentPackage ) ) ) ; } if ( ( this . noProposal ) && ( ( this . problem ) != null ) ) { this . requestor . completionFailure ( this . problem ) ; if ( CompletionEngine . DEBUG ) { this . printDebug ( this . problem ) ; } } return ; } ImportReference [ ] imports = parsedUnit . imports ; if ( imports != null ) { for ( int i = 0 , length = imports . length ; i < length ; i ++ ) { ImportReference importReference = imports [ i ] ; if ( importReference instanceof CompletionOnImportReference ) { this . lookupEnvironment . buildTypeBindings ( parsedUnit , null ) ; if ( ( this . unitScope = parsedUnit . scope ) != null ) { contextAccepted = true ; buildContext ( importReference , null , parsedUnit , null , null ) ; <START_BUG> long positions = importReference . sourcePositions [ ( ( importReference . sourcePositions . length ) - 1 ) ] ; <END_BUG>

Fix:
long positions = importReference . sourcePositions [ ( ( importReference . tokens . length ) - 1 ) ] ;